The domestic cat (Felis domesticus) lives successfully in desert conditions and is adapted to retain water by producing urine which is very concentrated compared to most other mammals. Producing highly concentrated urine, however, can have deleterious effects, such as enhancing development of urinary stones and other less well defined urinary tract conditions such feline idiopathic cystitis. A feline urinary tract condition due to poor hydration is sometimes referred to as Feline Lower Urinary Tract Disease (FLUTD). FLUTD can be a life-threatening condition for cats. In particular, a problem that cat owners face with FLUTD is that the disease is life-threatening to the cat by the time the symptoms are noticeable to the owner. Crystals can precipitate in the cat's urinary tract as stones and Obstruct it. Types of stones include struvite, calcium oxalate, urate, cystine, calcium phosphate, and silicate. Struvite and calcium oxalate stones are by far the most common in cats. If left untreated, a “block” cat will die, as the urine backs up and damages the kidneys, and toxins accumulate in the blood.
If the cat can be induced to drink more, this can dilute the urine and thereby ameliorate feline urinary conditions resulting from low hydration. This dilution acts at two levels: first, by reducing the electrolyte concentration in the urine (assuming the cat is not drinking more simply to compensate for higher dietary salt), and then by increasing micturition frequency and therefore reducing the amount of time spent by the urine in the bladder. Cats generally drink only about 30 milliliters of water per kilo of body weight per day, and it is difficult to increase spontaneous drinking Providing moist food helps to increase water intake in an animal that does not drink very much, but it is not sufficient, either because there is still not enough water ingested or because it does not sufficiently increase diuresis. In addition, cats exhibiting a urological syndrome are often obese or carry excess weight. Thus, when it is desired to treat urinary disorders, and in particular FLUID, providing a moist food may be preferable, but it is not sufficient, i.e., the food does not provide sufficient hydration, may not be accepted by the cat, or even may induce an additional excess weight and/or obesity if the amount distributed is poorly controlled.
Certain cat foods which contain certain omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (“DHA”) and eicosapentaenoic acid (“EPA”) are known, e.g., as disclosed in U.S. Pat. No. 8,252,742. Certain cat foods are also known to contain both omega-3 and omega-6 polyunsaturated in particular amounts and ratios such as disclosed in U.S. Pat. No. 6,946,488. However, there is no disclosure in the prior art of any effect of such fatty acids in the diet on hydration.
Therefore, there exists today a need for methods and compositions to increase hydration in cats, thereby treating, reducing, inhibiting or ameliorating urinary conditions such as FLUID.